Magnetism Experiments
Index Comparing the Strengths of Magnets
3
Electromagnet
4
Electromagnetic Motor
5
Electromagnetism
6
Field Blockers
7
Levitating Disks
9
Magnetic Field Lines
10
Why Compasses Work
11
Magnetism and the Care of Magnets
12
Supply List
13
References
14
Children’s Literature
15
Notes
16
Comparing the Strengths of Magnets
Index
Magnets vary in strength. This experiment uses a comparison of the number of paper clips each magnet can pick up to compare the strength of a variety of magnets.
Materials
Variety of magnets Metal paperclips
What To Do
Have the students predict which magnet will be the strongest, and which is the weakest. Make a pile of paperclips on a table or desktop. Lay a magnet on top of the pile, then pick it up slowly. Move the magnet and the paperclips stuck to it away from the original pile and take off the paperclips. Count how many the magnet picked up. Repeat with all the magnets, and decide which magnet is the strongest.
Questions
1. Which magnet was predicted to be the strongest? Was the prediction correct? What was the prediction based on? (Size? Weight? Color?) 2. Was the largest magnet also the strongest magnet? Was the smallest also the weakest? 3. Why are some magnets stronger than others?
Source
“Science Experiments With Magnets.” Sally Nankivoll-Aston and Dorothy Jackson, Franklin Watts Grolier Publishing, New York, 1999, p. 10. ISBN 0-531-14576-X © S. Olesik, WOW Project, Ohio State University, 2001.
Electromagnet
Index
Is it possible to make a temporary magnet with the use of electricity? Using the electrical field produced from a battery, it is possible to create a temporary magnet. Because electric currents induce magnetic fields, wrapping a coil of wire around an object such as a nail and connecting it to a battery can create a magnet. The benefit of this type of magnet is that it can be turned on and off when it is needed. Many uses of electromagnets are in use today such as many doorbells, telephones, and in junkyards to pick up magnetic objects.
Materials
Nail Metal paperclips or staples 1/2 meter of insulated wire 2 batteries 2 battery holders 2 alligator clips
What To Do
Take the wire and wrap it around the nail making a coil. Make sure to leave about two inches of unwound wire on each end and to wrap the coils tightly and close together. Before connecting the wire to the battery, try to use the nail to pick up the paperclips or staples. Does it work?Connect the two batteries in series by clipping the holders together. Attach an alligator clip to each end of the battery assembly, and connect wire leads from the coil around the nail to the other ends of the alligator clips. Now try to use the nail to pick up the paperclips or staples? Does it work? Reverse the connections on the wire leads so that electricity flows through the coil in the opposite direction. Watch closely to observe what happens.
Questions
1. Was the nail a stronger magnet before or after it was connected to the battery? 2. Why did the nail act better as a magnet after the battery was connected? 3. How would the strength of the electromagnet change if more batteries were used? What if less were used? 4. What changed in the nail to make the paperclips fall off when the direction of current flowing through the coil was reversed?
Summary
Using the electricity of the battery, we were able to make a temporary magnet. Electric currents induce magnetic fields. Wrapping the wire into a coil concentrated and strengthened the magnetic field, and having the iron nail in the center of the coil further strengthened the field. The field created by the flow of electricity was transferred to the nail by induction, and the nail acted as a magnet. Today, we use the reverse process of using a magnet to make electricity in many household items.
Source
“Magnet Science.” Glen Vecchione, Sterling Publishing Company, New York 1995, p.34-35, 61-62. ISBN 0-8069-0888-2 “Exploring Magnets.” Ed Catherall, Steck-Vaughn Co., Austin, 1990, p. 40-41. ISBN 0-8114-2593-2 “Awesome Experiments in Electricity and Magnetism.” Michael DiSpezio, Sterling Publishing Company, New York 1998 p. 108-109. ISBN 0-8069-9819-9 © S. Olesik, WOW Project, Ohio State University, 2001.
Electromagnetic Motor
Index
Electric motors are very useful, clean and versatile and are composed of three major parts. Every electric motor must have a current source, a magnet and a loop of coil. The motor transforms the potential energy of the power source into mechanical energy for rotating the coil. This activity will examine a small electromagnetic motor from how it is made to why it works.
Materials
D cell battery Battery holder designed with magnet holder and leads for the coil connections Magnet that fits in the holder 3 1/2 ft Copper wire, varnished Small piece of sandpaper
What To Do
Make a coil by wrapping the length of copper wire around and around the D cell battery. Leave slightly more than an inch of wire at each end to use to secure the coil and form leads. Take one end of the wire and wrap it around the coil to prevent it from coming apart. On the opposite side of the coil, half way around the circle, use the other end to secure the coil in the same way. The lead wires should stick out from opposite sides of the secured coil. Lay the coil on the table and rub the top of each lead with sandpaper, but do not turn over to remove the varnish on the opposite side. Insert the battery and the magnet into the holder. Place the coil in the holder by inserting the leads into the slots. What happens? A gentle push might be needed to begin the spinning, or it might work better if the leads were set on the other sides. Sometimes the lead wires might just need to be straightened or adjusted.
Questions 1. 2. 3. 4.
What happens when the motor starts to work? Why? How? Does the motor work if the magnet is left out of the assembly? Does the motor work if the coil is any shape other than a circle? Try an oval or a rectangle. How can a motor like this one be useful?
Summary
Electric current induces a magnetic field. The battery and the coil form a closed circuit when the leads are in contact with the holder slots, so there is electricity flowing through the coil creating a magnetic field. The magnetic field produced by the current in the coil interacts with the field of the permanent magnet, causing the coil to turn. The varnish that remains on one half of each of the lead wires serves to interrupt the flow of electricity with every turn the coil makes. When the unvarnished portion of the lead makes contact, electricity flows through the coil, causing the interactions that make it spin. When it spins the unvarnished portion of the lead makes contact, cutting off the flow of electricity. The coil continues to spin due to inertia, the starting point is reached again, and the coil receives another push when the electricity again begins to flow. Without the disruption in the electric flow, the coil would not spin. The force would push the coil in one direction and it would remain in that position.
Source
“Teaching Physics with Toys.� Beverley A.P. Taylor, James Poth and Dwight J. Portman, Terrific Science Press, McGraw-Hill, Middletown, 1995, p. 257-261. Š S. Olesik, WOW Project, Ohio State University, 2001.
Electromagneticism
Index
Did you know that electric currents induce magnetic fields? Whenever electricity is flowing it produces magnetic effects. In this experiment, students will observe the effect of magnetic fields generated by current flowing through a wire.
Materials
1 battery 1 battery holder 2 alligator clips Compass Bare wire
What To Do
Attach an alligator clip to one end of a battery and connect the other clip to the other end of the battery. Connect the loose ends of each alligator clip to a short length of bare wire. Hold the bare wire over a compass and watch the compass needle move. The needle will point at a right angle from the wire.
Questions
1. How does it work? 2. Why does the compass needle move when the compass is near the wire? 3. Do you think that when a compass is near a strong electric field (i.e. high tension wires) it is still able to tell you accurately which direction you are facing?
Source
“Magnets to Generators.” Peter Lafferty, Gloucester Press: New York 1989, p. 20. ISBN 0-5311-7165-5 © S. Olesik, WOW Project, Ohio State University, 2001.
Field Blockers
Index
Is there any way to shield or block magnetic forces? Magnetic fields can pass through a variety of materials, sometimes with no change in strength. Some materials, called ferromagnetic materials, work to change the direction of a magnetic field, and are therefore capable of containing the fields. This activity will help determine which types of materials are effective magnetic field blockers.
Materials
2 strong magnets (Neodymium or Alnico) Paperclips Thread Tape Thin wooden board A variety of materials to test, both magnetic and nonmagnetic (i.e. pieces of paper, plastic, Styrofoam, cardboard, wood, glass, rubber, aluminum foil, cloth, and iron or steel) Note to Volunteers: Do not allow children to use the metal sheets – they are sharp, and may cut someone.
What To Do
Place the board on a desktop so that a few inches extend past the front edge of the desk. Stack books on the desk on top of the board to secure it. Position one of the strong magnets on top of the part of the board that extends over the edge, then carefully place the other magnet on the bottom side of the board directly under the first magnet. Cut a piece of thread that is a few inches longer than the distance from the desktop to the floor and tie one end of the thread to a paperclip. Use tape to secure the other end of the thread to the base of the leg of the desk that is nearest the overhanging magnets. Pick up the paperclip and slowly move it up toward the magnets. How far from the magnets can you feel the strength of their fields? The magnets are strong enough to support the weight of the paperclip even if the paperclip is positioned about an inch away from the magnets. Hold the paperclip about an inch below the magnets and slowly pull it down and away from the magnets. Find out how far the magnetic fields extend with the strength to hold on to the paperclip. Tighten the thread so the paperclip floats in the air as far below the magnets as possible. The gap between the bottom magnet and the paperclip floating beneath it is where test materials will be inserted to determine their field blocking ability. Carefully place a test material between the paperclip and the magnet. Observe the paperclip. Is it held as tightly as before? Does it fall? Repeat above with each test material, being careful not to bump the paperclip with the test materials and recording all observations.
Questions
1. Which materials allowed the magnet to hold on to the paperclip? What do these materials have in common? 2. Which materials made the paperclip fall (i.e. which materials were effective field blockers?) 3. What do these materials have in common? How are they different from the materials that allowed the paperclip to remain in the air? 4. Why do some materials shield magnetic fields and others do not? 5. Which of the materials were attracted to the magnet? Which materials were the best field blockers?
Summary
Magnetic fields will flow through most materials, although better through some than others. In fact, some materials that insulate electricity do not insulate magnetic fields. Magnetic fields, because they are not insulated well by many materials, are contained and controlled by using ferromagnetic materials such as iron or steel to change their direction. Magnetic fields move very easily through ferromagnetic materials , which have low reluctance, and not so easily through other materials like cloth, paper, glass, and wood, which have high reluctance. The “path of least resistance” is often favored, so the magnetic force will be drawn into ferromagnetic materials rather than other materials if given the choice. In this way, a scientist may control magnetic fields using low reluctance materials to guide them.
Source
“Magnet Science.” Glen Vecchione, Sterling Publishing Company, New York 1995, p.40-41. ISBN 0-8069-08882 “The Magnet Book.” Shar Levine and Leslie Johnstone, Sterling Publishing Company, New York 1997, p. 18-19. ISBN 0-809-9943-8 © S. Olesik, WOW Project, Ohio State University, 2001.
Levitating Disks
Index
Opposite poles of magnets attract and like poles repel. The power of this statement can clearly be observed in this activity. If the like poles of two magnets are brought together they will repel, or push away from each other. The strength of the repulsion depends upon the strength of the magnets, and in this case is strong enough to overcome gravity.
Materials
3 or more circular magnets with holes in the middle Modeling clay or Styrofoam Pencil
What To Do
Make a base out of Styrofoam by cutting a small square (3” x 3”) or modeling clay by making a medium sized ball. Insert the sharpened end of the pencil into the modeling clay or Styrofoam base so the pencil sticks straight up. Slide one magnet onto the pencil, North pole facing downward. Slide the next magnet onto the pencil with the South pole facing down. Place the last magnet on the pencil, on top of the other two magnets, with the North pole facing down.
Questions 1. 2. 3. 4.
Why do the magnets float? What happens if one of the magnets is placed on the pencil in the reverse order or upside down? How many magnets could be stacked up and still float? Share magnets with a friend to find out. What uses exist or could be invented for magnetic levitation?
Summary
The magnets are stacked with like poles facing each other. The repulsion between like poles was strong enough to overcome the force of gravity and push the magnets apart.
Souce
“The Magnet Book.” Shar Levine and Leslie Johnstone, Sterling Publishing Company, New York 1997, p. 73. ISBN 0-809-9943-8 © S. Olesik, WOW Project, Ohio State University, 2001.
Magnetic Field Lines
Index
This experiment will help students visualize and understand the invisible fields surrounding magnets of various shapes.
Materials
Bar magnet Round magnet Horseshoe magnet Iron Filings Transparent page protector sleeve Tape
What To Do
Open the page protector sleeve and pour in a small amount of iron filings. Tape the sleeve shut, completely closing all openings so the filings cannot spill. While holding the sleeve horizontally, gently shake it to spread out the iron filings. Hold the sleeve level just above a magnet and gently tap it a few times. The filings should form a pattern that shows the lines of the magnetic field. Make a drawing of the magnetic field line pattern for the bar magnet. Repeat steps 2-4 with the round and horseshoe magnets. Compare the patterns of field lines for the various shapes of magnets.
Questions
1. Do you see the different patterns of the fields? Describe how they are similar and how they are different. 2. Why are more filings concentrated around the poles of the magnets? 3. Do the north and south poles of a magnet attract iron equally? 4. What can you tell about a magnet’s strength by looking at the shape of its magnetic field?
Summary
The shape of a magnet’s field can be studied by using iron filings to make the invisible forces visible. The small pieces of iron line up along the lines of the magnetic field. Conventionally, these lines of force are thought of as loops that flow out of the North pole of the magnet and into the south pole, with part of the loop outside the magnet and part of the loop inside the magnet. The strength of the field is proportional to the distance between the lines. The closer the lines are to each other, the stronger the field is. The higher concentration of filings collecting at the poles shows lines that are very close together and a strong part of the field. In the area between the poles, like the middle of a bar magnet, the lines are further apart, showing a weaker part of the field.
Source
“Magnet Science.” Glen Vecchione, Sterling Publishing Company, New York 1995 p. 29-30 ISBN 0-8069-0888-2 “The Science Book of Magnets.” Neil Ardley, Gulliver Books Harcourt Brace and Company, San Diego, 1991, p. 16 ISBN 0-15-200581-1 © S. Olesik, WOW Project, Ohio State University, 2001.
Why Compasses Work
Index
The earth is a very large magnet. The magnetic field of the earth originates in the molten core at the center of the planet. The hot, liquid metals of the core move around, creating electrical currents, which in turn induce a magnetic field. It has a north pole and south pole, just as bar magnets do, but they are not quite the same as the North Pole and South Pole one can see on a map marking the axis around which the earth rotates. The magnetic poles of the earth are located about 1000 miles away from the geographic poles, and the pole nearest the geographic north pole is actually the south pole of the earth’s magnetic field. It attracts the North poles of all other magnets and repels the South poles. Compass needles are magnetized, and the North pole of the compass needle is attracted to the South Pole of the earth’s magnetic field, near the geographic North Pole. Make a simple water compass to test this.
Materials
Sewing needle Bar magnet Styrofoam Plastic cup or bowl Water Compass
What To Do
Magnetize a sewing needle by repeatedly stroking it in the same direction with the same pole of a bar magnet. Do not rub the magnet back and forth across the needle – it will not work! Cut a small piece of Styrofoam and push the sewing needle through it so that both ends can be seen. Float the Styrofoam/needle in a cup of water. What direction does the needle point? Try turning the needle around. Does it always come back to point in the same direction? Try turning the cup around. What does the needle do?Compare the direction the needle points to the direction the compass points.
Questions
1. What direction did the needle point? Why? 2. Did it always point in the same direction? 3. Would the needle point in the same direction if the other end of the bar magnet had been used to magnetize it? 4. Did the needle and the compass point in the same direction? 5. What happens if a magnet is brought near the side of the cup?
Summary
The magnetized needle should line up in a North-South direction when allowed to align itself freely in the water. A compass was made and can be verified by comparing it to a compass bought from the store.
Source
“The Magnet Book.” Shar Levine and Leslie Johnstone, Sterling Publishing Company, New York 1997 p. 73 ISBN 0-809-9943-8 “The Science Book of Magnets.” Neil Ardley, Gulliver Books Harcourt Brace and Company, San Diego, 1991, p. 24-25. ISBN 0-15-200581-1 © S. Olesik, WOW Project, Ohio State University, 2001.
Magnetism
Index
Atoms are the smallest particles of matter. Each atom acts as a tiny magnet with a North and South pole. In a magnetic material, there are regions where the atoms are grouped together with the north poles of the atoms attracted to the south poles. In an unmagnetized material the regions are randomly distributed. The atoms in a solid are always in motion but in magnetic solids the atoms still remain aligned to each other even with the motion. However, if the solid is heated the motion increases and at a certain temperature the motion becomes so great that the alignment is lost. This temperature is called the Curie Temperature.
Materials
Magnetic material (unmagnetized) Weak magnet Strong magnet
Care of Magnets
Magnetic materials are inherently brittle. Therefore dropping them may cause breakage and will increase the probability of demagnetization. Magnets come with “keeper� plates, which are typically thin pieces of metal. Magnets should always be stored with keeper plates across the poles. The red/metal bar magnets and the horseshoe magnets should be stored with keeper metal pieces across the ends. Without the keeper plates, the alignment of the domains within the magnet will slowly drift out of line.
Source
Š S. Olesik, WOW Project, Ohio State University, 2001.
Index
Supply List Comparing the Strengths of Magnets Variety of magnets Metal paperclips
Electromagnet
Nail Metal paperclips or staples ½ meter of insulated wire 2 batteries 2 battery holders 2 alligator clips
Electromagnetic Motor
D cell battery Battery holder designed with magnet holder and leads for the coil connections Magnet that fits in the holder 3 ½ ft Copper wire, varnished Small piece of sandpaper
Electromagnetism 1 battery 1 battery holder 2 alligator clips Compass Bare wire
Field Blockers
2 strong magnets (Neodymium or Alnico) Paperclips Thread Tape Thin wooden board A variety of materials to test, both magnetic and nonmagnetic (i.e. pieces of paper, plastic, Styrofoam, cardboard, wood, glass, rubber, aluminum foil, cloth, and iron or steel)
Levitating Disks
3 or more circular magnets with holes in the middle Modeling clay or Styrofoam Pencil
Magnetic Field Lines
Bar magnet Round magnet Horseshoe magnet Iron Filings Transparent page protector sleeve Tape
Why Compasses Work Sewing needle Bar magnet Styrofoam Plastic cup or bowl Water Compass
References
Index
“Science Experiments With Magnets.” Sally Nankivoll-Aston and Dorothy Jackson, Franklin Watts Grolier Publishing, New York, 1999. ISBN 0-531-14576-X “Teaching Physics with Toys.” Beverley A.P. Taylor, James Poth and Dwight J. Portman, Terrific Science Press, McGraw-Hill, Middletown, 1995 “Magnet Science.” Glen Vecchione, Sterling Publishing Company, New York, 1995. ISBN 0-8069-0888-2 “Awesome Experiments in Electricity and Magnetism.” Michael DiSpezio, Sterling Publishing Company, New York 1998. ISBN 0-80699819-9 “Exploring Magnets.” Ed Catherall, Steck-Vaughn Co., Austin, 1990. ISBN 0-8114-2593-2 “Magnets to Generators.” Peter Lafferty, Gloucester Press: New York, 1989. ISBN 0-5311-7165-5 “The Magnet Book.” Shar Levine and Leslie Johnstone, Sterling Publishing Company, New York, 1997. ISBN 0-809-9943-8 “The Science Book of Magnets.” Neil Ardley, Gulliver Books Harcourt Brace and Company, San Diego, 1991. ISBN 0-15-200581-1
Index
Supply Lists Circuit Quiz Game Cardstock 2 batteries 2 battery holders 4 alligator clips 1 flashlight bulb 1 bulb holder Aluminum foil Tape Plastic film
Conductors and Insulators 1 battery 1 battery holder 1 flashlight bulb 1 bulb holder 3 alligator clips Cardboard Metal thumbtacks or brads Coins Keys Cork Buttons Fabric Screws Marbles Plastic String
Connect the Circuit Game
Bare wire or metal clothes hanger 1 flashlight bulb 1 bulb holder 2 batteries 2 battery holders Insulated wire Cardboard Tape Clay (if using the clothes hanger) Steel wool (if using the clothes hanger)
Electric Currents and Magnetic Fields 10 yards of insulated copper wire Wire strippers Tape Thread Magnet Beverage can Battery
Electroscope
Clear plastic cup Aluminum foil Metal paperclip Modeling clay or plastic tape Balloon Scissors
Lemon Battery
6 lemons 7 alligator clips 6 pennies 6 large metal paperclips Knife Voltmeter Light emitting diode (LED) that requires low voltage and low current Calculator that requires low voltage and low current
Parallel and Series Circuits 2 2 4 4 7
batteries battery holders bulbs bulb holders alligator clips
Simple Circuit 1 1 1 1 2
battery battery holder bulb bulb holder alligator clips
Static Electricity Balloons String Paper Plastic comb Wool Ping-pong balls Puffed rice Soap bubbles Salt and pepper
References
Index
“Power Up.” Sandra Markle, Atheneum: New York, 1989, p. 24. “The Science Book of Electricity.” Neil Ardley, Harcourt Brace and Company: London, 1991. “Science Experiments with Electricity.” Sally Nankivell-Aston and Dorothy Jackson, Franklin Watts: New York, 2000. “Awesome Experiments in Electricity and Magnetism.” Michael DiSpezio, Sterling Publishing Co.: New York, 1998. “Edison Etc.” The Wild Goose Company: Salt Lake City, 1994. “How Science Works,” Judith Hann, Reader’s Digest, Dorling Kindersley Limited, 1991.
Children’s Literature
Index
“Electricity and Magnetism.” By Peter Adamczyk and Paul-Francis Law. Usborne Publishing Ltd.: London, 1993. “All About Electricity.” By Melvin Berger, illustrated by Marsha Winborn. Scholastic Inc.: New York, 1995. ISBN 0-590-48077-4. “Switch On, Switch Off.” By Melvin Berger, illustrated by Carolyn Croll. Harper & Row, Publishers, Inc.: New York, 1989. ISBN 0-690- 04786-X. “The Magic School Bus and the Electric Field Trip.” By Joanna Cole, illustrated by Bruce Degan. Scholastic, Inc.: New York, 1997. ISBN 0-590-44682-7. “Shocking Science: Fun and Fascinating Electrical Experiments.” By Shar Levine and Leslie Johnstone, illustrated by Emily S. Edliq. Sterling Publishing Co., Inc.: New York, 1999. ISBN 0-8069- 3946-X. “Super-Charged Science Projects: Electromagnets in Action.” By Parramon’s Editorial Team. Barron’s Educational Series, Inc.: Hauppauge, 1994. ISBN 0-8120-6437-2. “Electricity.” By Simon de Pinna, photography by Chris Fairclough. Raintree Steck-Vaughn Publishers: Austin, 1998. ISBN 0-8172- 4945-1. “The Usborne Illustrated Encyclopedia: Science and Technology.” Usborne Publishing: London, 1996. “The Usborne Internet-Linked Library of Science: Light, Sound & Electricity.” By Kirsteen Rogers, Phillip Clarke, Alastair Smith, and Corinne Henderson. Usborne Publishing: London, 2001. “Fascinating Science Projects: Electricity and Magnetism.” By Bobbi Searle. Copper Beech Books: Brookfield, 2002. ISBN 0-7613- 1630-2. “Electricity and Magnetism.” By Robert Snedden. Heinemann Library: Chicago, 1999. ISBN 1-57572-868-0. “Janice Van Cleave’s Electricity: Mind-Boggling Experiments You Can Turn Into Science Fair Projects.” By Janice Van Cleave. John Wiley & Sons, Inc.: New York, 1994. ISBN 0-471-31030-7.
Index
Notes
There are currently no notes on this unit. If you have suggestions or changes to make on the experiments or units, please email us! Our address is wow@chemistry.ohio-state.edu. Š S. Olesik, WOW Project, Ohio State University, 2002.
Copyright Š 2002-2010 by S.Olesik, Wonders of Our World Project (WOW), the Ohio State University. Permission to make digital or hard copies of portions of this work for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page in print or the first screen in digital media. Abstracting with credit is permitted.
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